diff --git a/libethcore/Common.cpp b/libethcore/Common.cpp
index 02e806905..572ade3e2 100644
--- a/libethcore/Common.cpp
+++ b/libethcore/Common.cpp
@@ -36,7 +36,7 @@ namespace eth
 const unsigned c_ethashVersion = c_ethashRevision;
 const unsigned c_protocolVersion = 60;
 const unsigned c_minorProtocolVersion = 0;
-const unsigned c_databaseBaseVersion = 8;
+const unsigned c_databaseBaseVersion = 9;
 #if ETH_FATDB
 const unsigned c_databaseVersionModifier = 1;
 #else
diff --git a/libethereum/BlockChain.cpp b/libethereum/BlockChain.cpp
index cad23171a..74aeb4fad 100644
--- a/libethereum/BlockChain.cpp
+++ b/libethereum/BlockChain.cpp
@@ -21,6 +21,9 @@
 
 #include "BlockChain.h"
 
+#if ETH_PROFILING_GPERF
+#include <gperftools/profiler.h>
+#endif
 #include <leveldb/db.h>
 #include <boost/timer.hpp>
 #include <boost/filesystem.hpp>
@@ -65,7 +68,7 @@ std::ostream& dev::eth::operator<<(std::ostream& _out, BlockChain const& _bc)
 	return _out;
 }
 
-ldb::Slice dev::eth::toSlice(h256 const& _h, unsigned _sub)
+ldb::Slice dev::eth::oldToSlice(h256 const& _h, unsigned _sub)
 {
 #if ALL_COMPILERS_ARE_CPP11_COMPLIANT
 	static thread_local h256 h = _h ^ sha3(h256(u256(_sub)));
@@ -79,6 +82,21 @@ ldb::Slice dev::eth::toSlice(h256 const& _h, unsigned _sub)
 #endif
 }
 
+ldb::Slice dev::eth::toSlice(h256 const& _h, unsigned _sub)
+{
+#if ALL_COMPILERS_ARE_CPP11_COMPLIANT
+	static thread_local h256 h = _h ^ sha3(h256(u256(_sub)));
+	return ldb::Slice((char const*)&h, 32);
+#else
+	static boost::thread_specific_ptr<FixedHash<33>> t_h;
+	if (!t_h.get())
+		t_h.reset(new FixedHash<33>);
+	*t_h = FixedHash<33>(_h);
+	(*t_h)[32] = (uint8_t)_sub;
+	return (ldb::Slice)t_h->ref();//(char const*)t_h.get(), 32);
+#endif
+}
+
 #if ETH_DEBUG
 static const chrono::system_clock::duration c_collectionDuration = chrono::seconds(15);
 static const unsigned c_collectionQueueSize = 2;
@@ -148,7 +166,7 @@ void BlockChain::open(std::string const& _path, WithExisting _we)
 		}
 	}
 
-	if (!details(m_genesisHash))
+	if (_we != WithExisting::Verify && !details(m_genesisHash))
 	{
 		// Insert details of genesis block.
 		m_details[m_genesisHash] = BlockDetails(0, c_genesisDifficulty, h256(), {});
@@ -178,7 +196,6 @@ void BlockChain::close()
 	m_blocks.clear();
 }
 
-#include <gperftools/profiler.h>
 #define IGNORE_EXCEPTIONS(X) try { X; } catch (...) {}
 
 void BlockChain::rebuild(std::string const& _path, std::function<void(unsigned, unsigned)> const& _progress)
@@ -187,6 +204,7 @@ void BlockChain::rebuild(std::string const& _path, std::function<void(unsigned,
 	ProfilerStart("BlockChain_rebuild.log");
 #endif
 
+//	unsigned originalNumber = (unsigned)BlockInfo(oldBlock(m_lastBlockHash)).number;
 	unsigned originalNumber = number();
 
 	// Keep extras DB around, but under a temp name
@@ -968,3 +986,33 @@ bytes BlockChain::block(h256 const& _hash) const
 
 	return m_blocks[_hash];
 }
+
+bytes BlockChain::oldBlock(h256 const& _hash) const
+{
+	if (_hash == m_genesisHash)
+		return m_genesisBlock;
+
+	{
+		ReadGuard l(x_blocks);
+		auto it = m_blocks.find(_hash);
+		if (it != m_blocks.end())
+			return it->second;
+	}
+
+	string d;
+	m_blocksDB->Get(m_readOptions, oldToSlice(_hash), &d);
+
+	if (!d.size())
+	{
+		cwarn << "Couldn't find requested block:" << _hash.abridged();
+		return bytes();
+	}
+
+	WriteGuard l(x_blocks);
+	m_blocks[_hash].resize(d.size());
+	memcpy(m_blocks[_hash].data(), d.data(), d.size());
+
+	noteUsed(_hash);
+
+	return m_blocks[_hash];
+}
diff --git a/libethereum/BlockChain.h b/libethereum/BlockChain.h
index 2e2d8cf34..83b1926e8 100644
--- a/libethereum/BlockChain.h
+++ b/libethereum/BlockChain.h
@@ -64,6 +64,7 @@ struct BlockChainWarn: public LogChannel { static const char* name() { return "=
 std::map<Address, Account> const& genesisState();
 
 ldb::Slice toSlice(h256 const& _h, unsigned _sub = 0);
+ldb::Slice oldToSlice(h256 const& _h, unsigned _sub = 0);
 
 using BlocksHash = std::map<h256, bytes>;
 using TransactionHashes = h256s;
@@ -119,6 +120,7 @@ public:
 	/// Get a block (RLP format) for the given hash (or the most recent mined if none given). Thread-safe.
 	bytes block(h256 const& _hash) const;
 	bytes block() const { return block(currentHash()); }
+	bytes oldBlock(h256 const& _hash) const;
 
 	/// Get the familial details concerning a block (or the most recent mined if none given). Thread-safe.
 	BlockDetails details(h256 const& _hash) const { return queryExtras<BlockDetails, ExtraDetails>(_hash, m_details, x_details, NullBlockDetails); }
@@ -268,6 +270,30 @@ private:
 		return ret.first->second;
 	}
 
+	template<class T, unsigned N> T oldQueryExtras(h256 const& _h, std::map<h256, T>& _m, boost::shared_mutex& _x, T const& _n, ldb::DB* _extrasDB = nullptr) const
+	{
+		{
+			ReadGuard l(_x);
+			auto it = _m.find(_h);
+			if (it != _m.end())
+				return it->second;
+		}
+
+		std::string s;
+		(_extrasDB ? _extrasDB : m_extrasDB)->Get(m_readOptions, oldToSlice(_h, N), &s);
+		if (s.empty())
+		{
+//			cout << "Not found in DB: " << _h << endl;
+			return _n;
+		}
+
+		noteUsed(_h, N);
+
+		WriteGuard l(_x);
+		auto ret = _m.insert(std::make_pair(_h, T(RLP(s))));
+		return ret.first->second;
+	}
+
 	void checkConsistency();
 
 	/// The caches of the disk DB and their locks.
diff --git a/libethereum/Client.cpp b/libethereum/Client.cpp
index 95fd2364f..71a9a4dbe 100644
--- a/libethereum/Client.cpp
+++ b/libethereum/Client.cpp
@@ -123,7 +123,7 @@ Client::Client(p2p::Host* _extNet, std::string const& _dbPath, WithExisting _for
 	m_bc(_dbPath, max(m_vc.action(), _forceAction), [](unsigned d, unsigned t){ cerr << "REVISING BLOCKCHAIN: Processed " << d << " of " << t << "...\r"; }),
 	m_gp(new TrivialGasPricer),
 	m_stateDB(State::openDB(_dbPath, max(m_vc.action(), _forceAction))),
-	m_preMine(m_stateDB),
+	m_preMine(m_stateDB, BaseState::CanonGenesis),
 	m_postMine(m_stateDB)
 {
 	m_gp->update(m_bc);
diff --git a/libethereum/EthereumPeer.cpp b/libethereum/EthereumPeer.cpp
index 15ce5c3f6..ca0195efe 100644
--- a/libethereum/EthereumPeer.cpp
+++ b/libethereum/EthereumPeer.cpp
@@ -478,7 +478,12 @@ bool EthereumPeer::interpret(unsigned _id, RLP const& _r)
 		clogS(NetMessageSummary) << dec << success << "imported OK," << unknown << "with unknown parents," << future << "with future timestamps," << got << " already known," << repeated << " repeats received.";
 
 		if (m_asking == Asking::Blocks)
-			transition(Asking::Blocks);
+		{
+			if (!got)
+				transition(Asking::Blocks);
+			else
+				transition(Asking::Nothing);
+		}
 		break;
 	}
 	case NewBlockPacket: